Synthesis And Properties Of Bio-based Elastomers Based On Terpenoids

At present,the source of most of the rubber,except for natural rubber,is olefin monomers extracted from petroleum.But Chinese annual oil production is insufficient and heavily dependent on imports.In recent years,as the instability of the international situation increases,it had already significantly impacted on the stable supply of Chinese oil resources.In order to reduce the dependence of synthetic rubber on unsustainable petrochemical resources,many scholars at home and abroad have focused on natural compounds and bio-based monomers produced by biological fermentation.Terpenoids are the largest natural compounds,containing a variety of bio-based monomers,of which the most widely studied monomers is myrcene,scholars have synthesized myrcene polymers and their copolymers by active polymerization(anionic polymerization,cationic polymerization and coordination polymerization)and free radical emulsion polymerization.Based on this,we hope to expand the synthesis and application of terpene bio-based monomers,and to synthesiz myrcene-farnesene copolymers by coordination polymerization and emulsion polymerization,and the research content is as follows:In the first part of this paper,we synthesized myrcene-farnesene copolymer by coordination polymerization,with nickel-boron trifluoride-ether complex as the main initiator and tri-isobutyl aluminum as the initiator.We studied that the molecular structure,molecular weight and molecular weight distribution of myrcene-farnesene copolymers synthesized at different temperatures.It was found that the myrcene-farnesene copolymer synthesized by the active polymerization method had a low molecular weight and was in liquid form,which could be used as new bio-based macromolecular plasticizer.Therefore,we prepared the rubber nanocomposites by myrcene-farnesene copolymer plasticized emulsion styrene-butadiene rubber,and studied that the effects of the new bio-based plasticizer on the processing properties,static and dynamic mechanical properties and thermodynamic properties of emulsion polystyrene-butadiene nanocomposites.The results show that the molecular weight of the myrcene-farnesene copolymer synthesized by coordination polymerization is about 1.5×10~4g/mol,and the styrene-butadiene nanocomposites with the copolymer as plasticizer have a lower glass transition temperature(-49°C)and good ice slip resistance,which is expected to play a positive role in improving the low temperature resistance of tires.In the second part of this paper,we synthesized the myrcene-farnesene(PMYFA)copolymer by free radical emulsion polymerization,and studied that the effects of reaction temperature,initiator dosage,emulsifier type and monomer content on the molecular structure,molecular weight,latex particle size and glass transition temperature of the polymer in detail,optimized the polymerization reaction conditions.We prepared silica/PMYFA copolymer rubber nanocomposites,and systematically analyzed that their dynamic mechanical properties and thermodynamic properties.The results show that PMYFA synthesized by free radical emulsion polymerization has a higher molecular weight than the myrcene-farnesene copolymer synthesized by active polymerization,4～7×10~4g/mol,low glass transition temperature(<-70°C)and high compliance,the glass transition temperature of PMYFA nanocomposites with high farnesene monomer content can reach-68°C,which is expected to be applied in the field of low-temperature resistant rubber,and reduce the dependence of synthetic rubber on non-renewable petrochemical resources.